This study is looking for any long-term effects of drug therapy on growth, development, long-term survival, and quality of life. The purpose of this study is to follow children and teenagers who are or have been in pediatric ACTG research studies. This includes all babies born to human immunodeficiency virus (HIV) infected mothers who were enrolled in an ACTG drug study when they were pregnant, infants or children who received anti-HIV vaccines, and children and teenagers enrolled in the Long Term Survivors study (LTS) sponsored by the Pediatric AIDS Foundation. All children will be followed until their 21st birthday.